Needleless syringe devices are known from WO 94/24263. In this document, a needleless syringe is disclosed which entrains particles in a gas stream accelerated through a nozzle so that the particles may be injected into a target, such as human or animal skin or other cells. For many applications, there is a need for the particles to be maintained in a sealed and often sterile environment prior to actuation of the device. WO 94/24263 discloses a particle cassette comprising a central annular ring having rupturable membranes sealed to each face so as to form a self-contained sealed unit containing particles to be injected. Upon actuation of the device, the membranes rupture, allowing the particles initially contained between the membranes to be entrained in the gas flow and then delivered to the target. WO 94/24263 is hereby incorporated by reference.
An improvement to the particle cassette of WO 94/24263 is disclosed in WO 03/011379. In this document, a particle cassette comprised of two parts, each part having bonded thereto a rupturable membrane, is disclosed. In the preferred mode of manufacture, the membranes are heat-bonded to their respective cassette parts and the particle cassette is formed by bringing the cassette parts together so to create a chamber for the particles between the membranes. This overcomes the problem with the WO 94/24263 particle cassette that heat-bonding the second membrane to the annular ring can cause degradation of the particles in the chamber. WO 03/011379 is also hereby incorporated by reference.
The particle cassettes of WO 03/011379 comprise a minimum of four parts; a first cassette part, a first membrane bonded thereto, a second cassette part and a second membrane bonded thereto.
The initial step of bonding the first and second membranes to the respective first and second cassette parts is laborious. Initially, the first cassette part and first membrane have to be aligned with one another. Then, heat and pressure must be applied to bond the first membrane to the first cassette part. The same needs to be done for the second membrane and the second cassette part. Aligning the membranes with the respective cassette parts prior to bonding can be bothersome.
Another problem lies in accurately and quickly providing particles to the particle cassettes. One method for providing particles to a cassette part having a membrane bonded thereto is disclosed in WO 01/33176, the disclosure of which is hereby incorporated by reference. However, that method requires the cassette part (and attached membrane) to be placed on the weight measuring scale prior to particle dispensing and to be removed from the weight measuring scale after dispensation. This can be done manually although a mechanism for this purpose is shown in FIG. 20 of WO 01/33176. It should be appreciated that it is difficult in practice to implement such a mechanism with a high throughput of particle cassettes and which is reliable enough to grasp the particle cassette parts and carry them without spilling any particles. It can be especially difficult to orient the particle cassette parts properly on the weight measuring scales, especially if it is desired to bring the particle cassette parts to and from the scale at a high speed.
Furthermore, once the cassette parts have been bonded with their respective membrane, and one of the cassette parts has had particles provided to its chamber, it is necessary to relatively orient the first and second cassette parts before bringing them together to create a finished particle cassette.
Devices and methods which alleviate the laborious manufacturing process are thus desired.